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    <script>
        // 3. 写函数, 把传过来的列表中的每一个元素都用"_"拼接, 并返回
        function joint(){
            let joint = ''
            for(let i = 0; i < arguments.length; i++){
                joint = joint + arguments[i] + '_'
            }

            return joint
        }

        console.log(joint(1,2,3,4,5,6));

    </script>

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